Drilling bit for stacked sheets of paper and the like



June 18, 1968 F. A. RUDOLPH DRILLING BIT FOR STACKED SHEETS OF PAPER AND THE LIKE Filed Aug. 4, 1966 FREDERICK A. RUDOLPH ATTORNEY United States Patent 3,388,620 DRILLENG BIT FOR STACKED SHEETS OF PAPER AND THE LIKE Frederic A. Rudolph, 3115 NW. 24th St.,' Oklahoma City, Okla. 73107 Filed Aug. 4, 1966, Ser. No. 570,211 6 Claims. (CI. 7769) The present invention relates to cutting tools for drilling holes in stacked sheets of such material as paper, cardboard and the like and more particularly provides a novel hollow drill bit capable of simultaneously drilling through all the sheets of a stack of considerable thickness, forming holes fully equal in sharpness of cut and perfect circularity to the best products of the single sheet die cutting machines heretofore used.

The tool is a hollow drill bit provided with a conventional shank for application to the socket of any well known type of power drilling machine.

Its novelty resides in a unique arrangement for waste accommodation and ejection by a cut-out follower member including a presser head or follower mounted inside a cylindrical cutter member which has a terminal cutting edge. The follower head is rotatably mounted in the rotating cutter member so that during the power driven high speed rotation of the cutting edge the follower head normally remains rotationally stationary while receding axially as the cutter member advances into the stack of sheets. Thus the head exerts pressure on the central area of the cutting, holding the cut-outs against rotation and thus eliminating tendency to tear and multilate the cut, while yielding to accommodate the stack of cut-outs up into the tool for automatic ejection later, upon lifting of the drill from the completely drilled stack.

The details of the novel structure, and some of the principal advantages of the new drill, will become apparent to those skilled in the art from the following disclosure of a preferred embodiment of the invention which is illustrated in the accompanying drawings, in which:

FIGURE 1 is a side elevational view, partly in vertical central section, of the preferred embodiment of the invention applied to a conventional type of power drill and set in operative position about to initiate a drilling operation in a stack of paper sheets;

FIG. 2 is a cross sectional view taken on the line 2-2 of FIG. 1;

FIG. 3 is a relatively enlarged vertical sectional view, generally similar to that of FIG. 1 but showing the drill with the parts in the position assumed when the out has proceeded through a major portion of the stack; and

FIG. 4 is a perspective view of the inner member of the drill, with the cap detached and the stern partly brok en away.

In these drawings the reference numeral 1 designates generally a conventional power drill press of any suitable type having a socket or equivalent driven element 2 adapted to receive and drive a drill bit for forming holes in a stack of sheets of paper or the like. The present invention is concerned solely with the drill bit, and it is to be understood that any conventional or other mode of connection and application to a power drill press is contemplated. In the illustrated embodiment, showing the preferred form which has been used in actual practice and found to give entirely satisfactory results, this connection is shown as the shank of the outer member of the drill bit in which the invention resides, as will now be described.

The new drill bit comprises two principal parts: an outer member designated generally 3 and an inner member designated generally 4. The outer member is the cutting element. It is best made of a suitable tool steel and includes a cylindrical portion 5 at what may for conven- 3,388,620 Patented June 18, 1968 ience of description be considered its lower end and it has an integral shank 6 at its upper end. The shank also may be cylindrical as shown but it may be otherwise shaped, as for example it may be made polygonal in cross section, as may be required by the type of socket or other connection to the power machine that must be accommodated. It will ordinarily be considerably reduced in diameter from the lower portion 5.

The outer member 4 is axially open clear through with a continuous bore means that is counterbored variously as best shown by FIG. 3. The bore means is circular in cross section and is at its narrowest in the region of the junction of the shank 6 and lower portion 5. This narrowest portion of the bore means is designated 7 in the drawing. It is counterbored at 8 from the top, through the whole length of the shank 6, to provide an upper shoulder 9 in the lower part of the shank, and it is counterbored at 10 from the bottom, through the length of the lower portion 5, to provide a lower shoulder 11 extending through the major part of the lower portion.

In the preferred, illustrated embodiment of the invention the lower portion is further counterbored to provide two stepped enlargements of the bore means. The higher, or inner one is shown at 12, and the lower or bottom end enlargement is shown at 13. The latter is of such large diameter that the adjacent wall of the lower portion 5 is quite thin. The wall terminates in an internally beveled sharp cutting edge 14. The axial length of the bottom end enlargement 13 of the bore means, and that of the higher or inner enlargement 12, are determined by the depth of cut which the bit is designed to make and by the axial dimensions of certain parts of the inner member 4 which will now be described.

The inner member 4- includes a stem 29 in the form of a solid rod of a diameter that is adapted snugly to fit the narrowest portion 7 of the bore means for free rotation axial reciprocation. The upper end of the stem is tapped to receive the threaded shank of a machine screw 21 having a slotted head of a diameter only slightly less than that of the counterbore 8 of the outer member. The stem 20 terminates at its lower end in a follower head 22 comprising an integral lower disc 23 having a diameter snugly fitting the bottom end bore enlargement 13 and a superposed concentric socket 24 of a diameter that fits into the higher or inner enlargement 12 of the bore means. The follower head 22 is rotatably secured to the bottom end of the stem 20, and the preferred connection is by antifrietion means such as the ball bearing shown in FIG. 3. A satisfactory arrangement comprising an outer race 25 fixed in the socket 24, an inner race 26 fast on the end of the stem 20, and an intervening cluster of balls 27 maintained spaced in the usual manner. A dust cap 28 may be provided as a cover, and this in turn may be surmounted by a radial flange 29 formed on the stem.

It will be evident from the foregoing description that when the inner member 4 is installed in the outer member as shown in FIGS. 1 and 3, the inner member is free to slide or reciprocate axially in the bore means of the outer member and the follower head 22 of the inner member is free to rotate on the stem.

It will also be evident that installation is effected by inserting the stem 20, with the cap 21 removed, up through the bottom of the outer member and thereafter screwing the cap in place, so that its enlarged head will engage the shoulder 9 to limit downward movement of the inner member.

In order to keep the inner member normally in its lowermost position in the outer member, with the cap 21 engaged with the shoulder 9, a coil compression spring 35) is sleeved around the lower portion of the stem 20. This spring reacts in tension between the flange 29 at the lower end of the stem and the shoulder 11 at the upper end of the counterbore 10 of the outer member. It will be appreciated that the spring substantially fills the counterbore 10 and y-ieldably biases the follower head 22 downwardly. The several parts are so proportioned that when the inner member is projected to the limit permitted by engagement of the cap 21 with the upper shoulder 8 the follower head end disc 23 is substantially in the plane of the cutting edge 14 of the outer member. The axial depths of the bore enlargements 13 and 12 are such as to receive the disc 23 and socket 24 respectively when the inner member is raised to its limit in the outer member, the rise of the cap 21 in the counterbore 8 being accommodated by the length of that counterbore in the shank 2.

Moreover, the length of rise permitted the inner member by the relationship of inner member parts and cor responding outer member bore enlargements and c0un terbores is determined, in the design of the device, by the maximum depth of cut that is to be made, i.e., by the greatest thickness of a stack of sheets to be drilled.

Thus, in the operation of the device, the assembled drill bit is installed in a conventional power drilling machine by inserting its shank 8 into the machines socket 2 in the usual manner, and the stack of sheets S is set in position on the bed of the machine beneath the bit. When the bit and the stack are brought together, as shown in FIG. 1, the follower head will have its outer end surface (or the marginal zone thereof if the surface be centrally dished as is shown and preferred) lying substantially in the plane of the cutting edge 14, and this edge will engage the top sheet of the stack. Upon rotation of the outer member, and downward pressure of the bit on the stack, resulting from operation of the machine 1 in the usual way, the edge 14 cuts the sheets, descending into the stack as shown in FIG. 3, with the spring 30 pressing the follower head down against the stack but yielding to permit the whole inner member to rise in the bore means of the outer member as the disc cut-outs C rise in the bore enlargement 13. During this rotation of the outer member and its cutting edge, which of course is preferably at a high rate of speed, the follower head 23 Will remain non-rotatably engaged with the stack of cut-outs. Thus there is eliminated tearing, chewing, etc., of the sheets and distortion of the hole that is being drilled into them.

Upon termination of the cuttin operation and withdrawal of the bit from the stack, the spring 30 expands and ejects the cut-outs C from the bore enlargement 13, so that the bit is immediately ready for another drilling operation.

The spring 30 is preferably such as to exert quite strong thrust on the follower head. As such, it would tend to eject the whole inner member with some violence when the parts are being disassembled by unscrewing the cap 21 from the stem. To prevent this and facilitate disassembling, as well as subsequent reassembling, the stem 20 is provided with a radial hole 35 and the outer member 3 is provided with a similar radial hole 36. The two holes are so located that they will be in continuous alignment when the inner member is pushed up to or nearly to its inner limit. When it is desired to disassemble the parts, the inner member is pushed in until a pin, or an awl of small diameter (not shown), can be inserted into both holes and thus hold the inner member in its elevated position, with the spring 30 well compressed. The cap 21 can then be removed by a screwdriver inserted through the counterbore 8. Then, as the pin is carefully withdrawn, it is easy to control the expansion of the spring by holding the hand against the follower head 22 as it becomes pushed out of the outer member.

To assemble the parts, the inner member, with the screw 21 removed, is pushed up into the outer member until the two holes are aligned. Then the pin or awl is inserted into the holes, thus holding the inner member in place and the spring compressed while the screw is turned down into position on the top of the stem, whereupon the pin or awl is removed.

The invention has been depicted and explained in the foregoing preferred embodiment merely by way of exemplification of the inventive principl s. These can be incorporated in other and variously modified forms Without departing from the spirit of the invention as defined by the more broadly worded of the appended claims.

I claim:

1. A cutting tool for drilling a hole in a stack of sheets of paper stock comprising:

an outer member having at its upper end a shank portion and at its lower end a hollow cylindrical lower portion of enlarged outer diameter terminating in a circular cutting edge, said outer member having axial bore means formed continuously through it comprising an upper counterbore in said shank portion which is open to the upper end of the member and comprising also a counter bore in said lower cylindrical portion whereby an upper shoulder is formed at the junction of the upper counterbore and the adjacent portion of the axial bore means and a lower shoulder is formed at the junction of the lower counterbore and the adjacent portion of the axial bore means, in combination with an inner member comprising a stem snugly fitting the axial bore means between said shoulders for relative rotary movement in said bore means and having a cap of enlarged diamet r removable on its upper end positioned in the upper counterbore and engageable with the upper shoulder for limiting axial movement of the stem downwardly in said bore means, said inner member terminating at its lower end in a follower head rotatably mounted on the stem by anti-friction means and snugly fitting the hollow cylindrical lower portion of the outer member,

and a coil spring compressed between said follower head and said lower shoulder for biasing the head downwardly to the limit permitted by engagement of the stem cap with said upper shoulder and yieldable to permit limited movement of the head axial- 1y up into the outer member as the outer member rotates and the cutting edge penetrates the paper stock and cut-out discs thereof push up into the hollow lower cylindrical portion of the outer member, said antifriction means including ball bearing means interposed between the follower head and the lower end of the stem and comprising inner and outer races connected to the stem and head respectively and a plurality of balls operatively mounted between said races.

2. A cutting tool as claimed in claim 1 in which the cap is the head of a screw threaded axially into the upper end of the stem and rotatable by a screwdriver insertible through the upper end of the upper counterbore of the outer member.

3. A cutting tool as claimed in claim 1 in which the hollow cylindrical lower portion of the outer member is formed with a lowermost counterbore adapted to receive rotatable mounting means securing the follower head to the stem.

4. A cutting tool as claimed in claim 1 in which the ball bearing means is of a diameter intermediate those of the follower head and the stem and is receivable, upon compression of the spring, into a lowermost counterbore formed in the lower portion of the outer member.

5. A cutting tool as claimed in claim 1 in which the cap is the head of a screw threaded axially into the upper end of the stem and rotatable by a screwdriver insertible through the upper end of the upper counterbore of the outer member,

which includes ball bearing means interposed between the follower head and the lower end of the stem, said bearing means comprising inner and outer races connected to the stem and head respectively and a plurality of balls operatively mounted between said races,

said bearing means being of a diameter intermediate those of the follower head and the stem and being receivable, upon compression of the spring, into a lowermost counterbore formed in the lower portion of the outer member,

and the outer member and the stem being provided with radial holes adapted to be in alignment, when the spring is substantially compressed, for reception of a pin to hold the inner member fixed up in the bore means of the outer member and maintain the spring compressed during removal or replacement of the cap relative to the stem.

6. A cutting tool for drilling a hole in a stack of sheets of paper stock comprising:

an outer member having at its upper end a shank portion and at its lower end a hollow cylindrical lower portion of enlarged outer diameter terminating in a circular cutting, edge,

said outer member having axial bore means formed continuously through it comprising an upper counterbore in said shank portion which is open to the the upper end of the member and comprising also a counterbore in said lower cylindrical portion whereby an upper shoulder is formed at the junction of the upper counterbore and the adjacent portion of the axial bore means and a lower shoulder is formed at the junction of the lower counterbore and the adjacent portion of the axial bore means,

in combination with an inner member comprising a stern snugly fitting the axial bore means between said shoulders for relative rotary movement in said bore means and having a cap of enlarged diameter removable on its upper end positioned in the upper counterbore and engageable with the upper shoulder for limiting axial movement of the stem downwardly in said bore means,

said inner member terminating at its lower end in a follower head rotatably mounted on the stem, snugly fitting the hollow cylindrical lower portion of the outer member,

and a coil spring compressed between said follower head and said lower shoulder for biasing the head downwardly to the limit permitted by engagement of the stem cap with said upper shoulder and yieldable to permit limited movement of the head axially up into the outer member as the outer member rotates and the cutting edge penetrates the paper stock and cut-out discs thereof push up in to the hollow lower cylindrical portion of the outer member,

said outer member and the stem being provided with radial holes adapted to be in alignment, when the spring is substantially compressed, for reception of a pin to hold the inner member fixed up in the bore means of the outer member and maintain the spring compressed during removal or replacement of the cap relative to the stern.

References Cited UNITED STATES PATENTS 1,260,264 3/1918 Huszar 14423 XR 1,941,551 1/1934 Gjertsen 7769 XR FOREIGN PATENTS 904,860 3/1945 France.

FRANCIS S. HUSAR, Primary Examiner. 

1. A CUTTING TOOL FOR DRILLING A HOLE IN A STACK OF SHEETS OF PAPER STOCK COMPRISING: AN OUTER MEMBER HAVING AT ITS UPPER END A SHANK PORTION AND AT ITS LOWER END A HOLLOW-CYLINDRICAL LOWER PORTION OF ENLARGED OUTER DIAMETER TERMINATING IN A CIRCULAR CUTTING EDGE, SAID OUTER MEMBER HAVING AXIAL BORE MEANS FORMED CONTINUOUSLY THROUGH IT COMPRISING AN UPPER COUNTERBORE IN SAID SHANK PORTION WHICH IS OPEN TO THE UPPER END OF THE MEMBER AND COMPRISING ALSO A COUNTERBORE IN SAID LOWER CYLINDRICAL PORTION WHEREBY AN UPPER SHOULDER IS FORMED AT THE JUNCTION OF THE UPPER COUNTERBORE AND THE ADJACENT PORTION OF THE AXIAL BORE IN SAID LOWER CYLINDRICAL PORTION WHEREBY AN JUNCTION OF THE LOWER COUNTERBORE AND THE ADJACENT PORTION OF THE AXIAL BORE MEANS, IN COMBINATION WITH AN INNER MEMBER COMPRISING A STEM SNUGLY FITTING THE AXIAL BORE MEANS BETWEEN SAID SHOULDERS FOR RELATIVE ROTARY MOVEMENT IN SAID BORE MEANS AND HAVING A CAP OF ENLARGED DIAMETER REMOVABLE ON ITS UPPER END POSITIONED IN THE UPPER COUNTERBORE AND ENGAGEABLE WITH THE UPPER SHOULDER FOR LIMITING AXIAL MOVEMENT OF THE STEM DOWNWARDLY IN SAID BORE MEANS, SAID INNER MEMBER TERMINATING AT ITS LOWER END IN A FOLLOWER HEAD ROTATABLY MOUNTED ON THE STEM BY ANTI-FRICTION MEANS AND SNUGLY FITTING THE HOLLOW CYLINDRICAL LOWER PORTION OF THE OUTER MEMBER, AND A COIL SPRING COMPRESSED BETWEEN SAID FOLLOWER HEAD AND SAID LOWER SHOULDER FOR BIASING THE HEAD DOWNWARDLY TO THE LIMIT PERMITTED BY ENGAGEMENT OF THE STEM CAP WITH SAID UPPER SHOULDER AND YIELDABLE TO PERMIT LIMITED MOVEMENT OF THE HEAD AXIALLY UP INTO THE OUTER MEMBER AS THE OUTER MEMBER ROTATES AND THE CUTTING EDGE PENETRATES THE PAPER STOCK AND CUT-OUT FISCS THEREOF PUSH UP INTO THE HOLLOW LOWER CYLINDRICAL PORTION OF THE OUTER MEMBER, SAID ANTIFRICTION MEANS INCLUDING BALL BEARING MEANS INTERPOSED BETWEEN THE FOLLOWER HEAD AND THE LOWER END OF THE STEM AND COMPRISING INNER AND OUTER RACES CONNECTED TO THE STEM AND HEAD RESPECTIVELY AND A PLURALITY OF BALLS OPERATIVELY MOUNTED BETWEEN SAID RACES. 